1) Field of the Invention
This invention pertains to the field of optical modules, and more particularly, to a method of fixing a lens in an optical module.
2) Description of the Related Art
FIG. 1 shows an exemplary optical module 100. The optical module 100 is a so-called xe2x80x9cbutterfly module,xe2x80x9d so named because it has a plurality of electrical leads 105 (e.g., seven) extending from first and second sides 102, 104 on opposite sides of the optical module 100, and an output optical fiber 110 extending from a third side 106 generally perpendicular to the first and second sides 102, 104. The optical module 100 also includes platform 120 on which is mounted a laser diode 130 which supplies light output to an input aperture 112 of the optical fiber 110.
A critical characteristic of the optical module 100 is the alignment of the light output of the optical module 100 and the input aperture 112 of the optical fiber 110. Especially in the case of a single mode fiber, it is critically important that the light output of the laser diode 130 be precisely aligned with the input aperture 112 of the optical fiber 110.
In the optical module 100, a lens 140 (sometimes referred to as a micro-lens) focuses the light out of the laser diode 130 onto the input aperture of the optical fiber 110. It is important that the micro-lens 140 be located in precise alignment with the laser diode 130 the optical fiber 110. The optical module 100 also includes an optical isolator 180 for preventing light coming back out of the input aperture 112 of the target optical fiber 110 from going back into the laser diode 130.
However, in the prior art, when attaching the micro-lens 140 to the platform 120, the micro-lens 140 is subject to significant misalignment with respect to the laser diode 130 and the optical fiber 110.
Accordingly, it would be advantageous to provide an improved method of fabricating an optical module. In particular, it would be advantageous to provide such a method including an improved method of fixedly attaching a lens to a platform of the optical module such that the lens remains in precise alignment with a light source (e.g., a laser diode) and a target optical fiber even after it is attached or fixed to the platform. Other and further objects and advantages will appear hereinafter.
The present invention comprises a method for fabricating an optical module, including a method of fixedly attaching a lens to a platform of the optical module such that the lens remains in precise alignment with a light source (e.g., a laser diode) and a target optical fiber even after it is attached to the platform.
In one aspect of the invention, a method is provided for fabricating an optical module including a light source producing light, an optical fiber having an input aperture aligned to receive the light, a ferrule fit around an exterior of the optical fiber, a micro-lens assembly comprising a bridge and a micro-lens holder holding a micro-lens, and a platform. The method comprises holding the optical fiber in place at a desired location with respect to the laser diode; initially aligning the micro-lens to the laser diode to substantially optimize coupling of light into the input aperture of the optical fiber; inserting the bridge beneath the micro-lens holder on the platform; fixing the bridge to the platform; realigning the micro-lens to the laser diode to substantially optimize coupling of light into the input aperture of the optical fiber; and fixing the micro-lens holder to the bridge.